We have developed techniques to specifically radioactively label carbohydrate portions of cell membrane glycoproteins and glycolipids. By applying such methods followed by polyacrylamide gel electrophoresis and autoradiography, we have previously shown that purified populations of normal human blood leukocytes have characteristic and distinguishable surface glycoprotein patterns which clearly correlate with the stage of cellular maturation and activation and have shown that various cultured benign and malignant leukocyte cell lines can be characterized by their surface glycoprotein profiles. We have shown that the human leukemia cell line K562 is erythroid, can be induced to erythrocyte differentiation in vitro and is useful for the study of erythroid proteins. The specific aims of this proposal are: (1)\isolation and molecular and functional characterization of the human leukocyte surface glycoproteins GP120 and GP130; (2)\isolation and structural characterization of the Rho(D) antigen from human erythrocytes; (3)\clarification of the reason for the absence of the major surface-labeled leukocyte glycoprotein from lymphoblastoid cell lines established from an En(a-) individual (lacking glycophorin A from erythrocytes); (4)\study of the mechanism of O-glycosylation of glycophorin A; (5)\study of the specific interaction of E. coli IH1165 with glycophorin A from erythrocytes of blood group M; (6)\evaluation of the usefulness of glycophorin A as a marker of erythroleukemia; and (7)\development of a surface glycoprotein analysis in cases of human leukemia with emphasis on clonal evolution during relapses.